Electric clock



y 1935. B. E. LAWRENCE ET AL 2,008,105

ELECTRIC CLOCK Filed April 20, 1931 3 Sheets-Sheet 1 y 1935. B. E. LAWRENCE AL 2,003,105

ELECTRIC CLOCK Filed April 20, 1931 3 Sheets-Sheet 2 y 1935. B. E. LAWRENCE El AL 2,008,105

ELECTRIC CLOCK Filed April 20, 1931 3 Sheets-Sheet '3 Patented July 16, 1935 UNITED STATES PATENT OFFICE ELECTRIC cLocK Benjamin E. Lawrence and Benjamin Hayes, Chicago, 111., said Hayes assignor to said Lawrence 7 Application April 20, 1931, Serial No. 531,346

7 Claims.

actuated by the armature shaft of a synchronous motor,'and the speed of the latter is governed by the frequency of the exciting current. Electric clocks of this type heretofore in use have been adapted for operation by an alternating current of one frequencyand, therefore, could not indicate accurate time if used in connection with an alternating current of a different frequency. For this reason, if the manufacturer wanted to ship clocks into various localities in which the alternating current differed in frequency, it was necessary to carry in stock various different lots of clocks and to select the clocks from the proper lot before shipment.

The main objects of this invention are to provide an alternating current electric clock having improved means associated with its gear train for manually changing the gear ratio to adapt the clock for use in connection with alternating currents of several different frequencies, as, for instance, the principal frequencies of sixty, fifty and thirty cycles; to provide gear changing mechanism of this kind which may be readily operated by the purchaser of the clock with the same facility as resetting the hands of the clock; to provide an electric clock having an improved form of gear mechanism; and to provide an alternating current electric clock of simple construction which can be marketed at a comparatively low price.

An illustrative embodiment of this invention is shown in the accompanying drawings, where- 1n:

Figure- 1 is-a front elevation of an improved clock mechanism with portions broken away.

Fig. 2 is a horizontal section, taken on the line 2-2 of Fig. 1.

Fig. 3 is an enlarged detail, partly in section and partly in elevation showing one of the worm gears and its shaft.

Fig. 4 is a vertical section, taken on the line 4-4 of Fig. 2.

Fig. 5 is a vertical 55 of Fig. 1.

section, taken on the line Fig. 6 is a rear elevation of the clock on a reduced scale, certain outline.

parts being shown in dotted Fig. 7 is a fragmentary section, taken on the line 1-1 of .Fig. 1.

Fig. 8 is an enlarged fragmentary section taken on the line 88 of Fig. 4 and showing the intermediate driving unit.

Fig. 9 is a perspective view of the alarm armature and its supporting bracket.

taken on the line l0 Fig. 10 is an enlarged fragmentary section,

II) of Fig. 6.

The clock mechanism to which this invention is applied is intended to be housed in an ornamental casing, but the casing has been omitted from the drawings because it forms no part of the present invention.

In the improved clock herein shown, the hands are rotated by a train of gears which is driven by an improved synchronous motor through an intermediate gear unit in which one of the gears is changeable for varying the gear ratio to adapt the clock for use in connection with alternating currents of different frequencies.

The clock includes a supporting frame having a' front plate I secured to posts 2 which are mounted on a back plate 3 which is adapted to be secured to the .casing, not shown. Mounted on the front plate I,

are forwardly projecting on the inner end of hand 7 is mounted on the spindle. The minute a sleeve 12, which loosely embraces the outer end of the spindle 9 and which is rotated by a gear l3 which is supported on a hub 14 fixed on the sleeve I2. The gear I3 is frictionally secured to the hub M by a friction washer [5. Fast on adapted to mesh with the hub I4, is a gear 16 a pinion I! mounted on a manually rotatable shaft l8 for setting the hands. On the outer end of the shaft I8, is a knob I 9 forming a finger grip for use in turning the shaft and shifting it axially. urged inwardly by a spring 20 for The shaft 18 is normally positioning the pinion l1 out of engagement with the gear. l6.

Also fast on the hub I4, is a pinion 2| meshing with a gear 22, which is rotatably supported on a pin 23 secured to the front plate I. v the hub of the gear Formed on 12, is a pinion 24, which drives a gear 25 mounted on a sleeve 26 which carries the hour hand 8 and which is loosely supported on the minute hand sleeve l2.

The gears l8 and I3 are arranged to mesh with certain gears of the improved driving unit, hereinafter described, which is driven by the synchronous motor.

In the form shown, the improved motor includes a coil 21 wound on a core 28 which is secured at its ends to a pair of magnet pole pieces 29 disposed between the front plate I and back plate 3. The core is supported on the shanks 30 of spacers 3|, which extend between the pole pieces and the back plate 3. Other spacers 32 extend between the shanks 38 and the front plate I.

The inner opposed edges of the pole pieces adjacent. the upper ends ,thereof are arcuate and provided with the usual projections 33 surrounding similar projections on an armature or rotor' 34, which is fixed on a spindle 35. The spindle 35 is rotatable in improved self aligning bearings. One of the bearings is secured to the front plate I and the other is secured to a bracket 36 mounted.on the pole pieces. This bracket also supports the inner end of the second hand spindle 9. In the form shown, each of the improved self aligning bearings includes a ball 31 movably mounted in a socket 38, which is externally threaded for receiving a cap 39. An oiled washer 48 is located within the cap.

Mounted on the rear end of the spindle 35, is a knob 4|, by which the rotor is manually started. The back plate 3 is depressed adjacent the starting knob, as shown at 42, to provide a pocket in which the knob is located so as to prevent the clock from being accidentally stopped by fingers or other objects coming in contact with the knob.

In the specific form herein shown, the clock is of the non-self-starting type. In synchronous motors heretofore in use, various forms of socalled anti-hunting devices have been employed to facilitate manual starting. Such anti-hunting devices usually include a fly wheel or inertia element mounted on the armature shaft but capable of a limited-movement relative to the arma ture or rotor. In some prior clockmechanisms, the fly Wheel and rotor were frictionally connected together so as to permit a limited relative movement. Other prior devices employed mechanical movements in connection with the inertia means, such as governor bodies. Neither of such devices are'employed in the construction herein shown.

In the construction herein illustrated, the fly wheel is' connected to the rotor by a pin and slot connection which permits the desired limited a relative movement between these parts. Fixed on the armature spindle 35, is a hub 43 having loosely supported thereon a fly wheel 44 provided with a slot 45 for receiving a pin 46.l mounted on the rotor.

Mounted on the armature shaft 35, is a driving worm gear 46 which drives the changeable gear unit. The worm 46 is in the form of a helical spring which is pressed ontoa sleeve 41 which is fast on the armature shaft.

In the form shown, the improved intermediate gear unit comprises a pair of transversely disposed shafts 48 and 49 rotatably mounted in a meshes with the gear [3 for driving the minute hand sleeve l2 and the hour hand sleeve 26. Also mounted on the shaft 48, is a gear 53, which meshes with a worm 54, which is in the form of a spiral spring pressed on a sleeve 55 which is keyed 5 to the shaft 49. Also fixed on the sleeve 55, is a gear 56, which meshes with the gear ID for driving the second hand spindle 9.

Meshing with the driving worm 46'of the motor shaft, are three gears 51, 58 and 59 having hubs 68, 6! and 62, respectively, which are loosely supported on the shaft 49. The gears 51, 58 and 59 are of different sizes and are constantly driven by the motor worm 46 at respectively different speeds. In the preferred construction, the gear 51 has thirty teeth and is adapted to drive the shaft 49 when the synchronous motor is operated by an alternating currentof sixty cycles. The gears 58 and 59 have twenty-five and fifteen teeth, respectively, for driving the shaft 49 when the motor is operated bycurrents having frequencies of fifty and thirty cycles, respectively.

In addition to being rotatable on the bracket 58, the shaft 49 is also axially movable and is provided with a key 63 seated in a depression 64 formed in the shaft. The key 63 is in the form of a spring which is normally urged outwardly for engagement with any one of key slots 65, 66 and 61 formed in the hubs 68, 6| and 62, respectively. The key is shifted into the proper slot by the axial movement of the shaft 49. The shaft 49 is manually shifted by means of a crank 68 which engages a groove 69 formed in one end of the shaft. The crank is provided with a shaft 10 projecting through the rear plate 3. The crank may be turned by a screw driver inserted in a slot 1| formed in the outer extremity of the shaft 10. The slot 1| is adapted to register with suitable markings 12 on the rear plate 3 for indicating the frequency of the current for which the clock is set.-

In the construction herein shown, an improved alarm is provided which is actuated by the same electromagnet which actuates the rotor. This alarm mechanism forms the subject of the divi-' sional application of Benjamin E. Lawrence, Serial No. 595,243, filed February 26, 1932. The alarm includes the usual bell 13 mounted on 2. depending arm 14 which is formed on the front plate I. Coacting with the bell, is a hammer 15 on a vibrator spring 16 which supports anarmature 11 arranged to coact with the lower ends 18.! of the pole pieces 29. The vibrator armature may be retracted for stopping the alarm by a keeper 18 rotatably mounted on the rear plate 3. The keeper has a shoulder 19 adapted to be moved into effective engagement with a depending finger 88 on the vibrator armature. The keeper is provided with a handle 8| projecting through a slot 82 in the rear plate 3. The armature and vibrator spring are supported by a bracket 83 having bifurcated arms 84 secured to the shanks 30 of the spacers 3|. I

The improved time controlled mechanism for actuating the alarm includes a tripper lever 85 which is pivoted on a pin 86 mounted on one of the posts 2. The lower end of the tripper 85 is positioned so as to be adapted to hold the vibrator armature 11 in aretracted position.- The tripper is shifted by means of a collar 81 which is rotatably mounted on a shaft 88 supported on the frame plates l and 3. A helical spring 89 urges the collar 81 rearwardly for shifting the tripper 85 into position to release the alarm vibrator.

The collar 81 is manually shifted forwardly dial 98.

against the action of the spring 89, to retract the alarm vibrator, by means of a cam 90 which is fixed on the rotatable shaft 88. The cam 90 has a projection 9| which normally engages the opposed faceof the collar 87 as shown in Fig. 2. Formed in the collar 81, is a recess 92 adapted to receive the cam projection 9| so as to permit the release of the alarm vibrator.

The mechanism is arranged so that the clock gear train rotates the collar 87 in order to effect a time controlled release of the alarm vibrator. In the form shown, the collar 81 is keyed to a hub $33, which is rotatably supported on the shaft 88. fixed on the hub 93 is a gear 84 which is driven constantly by the pinion 24 which also drives the hour hand gear 25. The time at which 'the alarm armature is released is determined by the position of the cam 90. The cam 90 and its shaft are manually rotated for setting the alarm by means of a knob 95 mounted on the rear end of the shaft. The knob is threaded to the shaft so that, if an attempt is made to rotate the cam 90 in the wrong direction, the knob will be unscrewed and no injury will result to the mechanism. Accidental rotation of the shaft 88 is prevented by a friction washer 96 mounted on the shaft and engaging the rear plate 3. Fixed on the shaft 88, is an indicator 9! registering with a suitable dial 98 on the rear plate.

in operation, the speed of the rotor 34 depends upon the frequency of the working current. If the current has a frequency of sixty cycles, the ear 51 is locked to the shaft 49. For a current of fifty cycles, the gear 58 is locked to the shaft and, for a thirty cycle current, the gear 59 is locked to the shaft. By means of the crank 68, the shaft '39 is shifted axially to position its key 53 in lock ing engagement with any one of the gears. By this improved construction, the gear train, which turns the hands, may be driven at a constant speed when the synchronous motor is operated by currents of certain unlike frequencies.

To set the alarm, the knob 95 is rotated until the indicator 91 points to the desired time on the The cam projection 9| normally engages the opposed face of the collar 81 to hold the tripper 85 in position to retract the alarm armature 11. During the operation of the clock mechanism, the collar 81 is rotated by the gear train. At the set time, the recess 92 of the collar 81 registers with the cam projection SI and the collar is urged rearwardly by the spring 89, thereby rocking the tripper 85 to release the alarm armature 11. To shut off the alarm the keeper handle 8| is depressed to shift the shoulder 19 into engagement with the finger 88 for retracting the armature. i 1

Although but one specific embodiment of this invention has been herein shown and described, it will be understood thatcertain details of the construction shown may be altered or omitted without departing from the spirit ofthe invention. D

We claim:

1. An electric clock mechanism comprising a frame, a gear train, a bracket mounted on said frame, an axially movable shaft rotatably supported on said bracket, a sleeve keyed on said shaft and geared to said train, a plurality of intermediategearslooselymountedon said shaft and driven at respectively diiferent speeds, a key for operatively connecting said shaft with any one of said intermediate gears, and means for axially shifting said shaft into operative relation with any one of said intermediate gears.

2. An electric clock mechanism having hands and comprising a frame, an alternating current motor, a gear train, a bracket mounted on said frame, and a pair of shafts rotatably supported on said bracket, one of said shafts being geared to said train and also to the other shaft, said other shaft being geared to said motor and to one of said hands.

3. An electric clock mechanism having second, minute, and hour hands, a gear train actuating said hands, a frame, an electric motor, a bracket mounted on said frame, and a pair of shafts mounted on said bracket and geared to each other, one of said shafts being geared to said minute and hour hands, the other of said shafts being geared to said motor and also to said second hand.

4. An electric clock mechanismcomprising a frame, an alternating current motor, a gear train, a bracket mounted on said frame, and a pair of shafts rotatably supported on said bracket, one of said shafts being geared to said train and also to the other shaft, said other shaft being geared to said motor.

5. A single electric clock comprising an alternating current synchronous motor, a gear train, intermediate means geared to said motor for driving said train, and mechanism for changing the gear ratio between said motor and intermediate means whereby said train may be driven at one speed when said motor is operated by a current of any one of several standard frequencies.

6. A single electric clock comprising an alternating current synchonous motor, a gear train, intermediate means geared to said motor for driving said train, and. manually operable mechanism for changing the gear ratio between said motor and intermediate means whereby said train may be driven at one speed when said motor is operated by a current of any one of several standard frequencies.

7. A single electric clock comprising an alternating current synchonous motor, a gear train, and an intermediate gear unit connecting said train with said motor, part of said intermediate unit being changeable to vary the gear ratio between said motor and unit whereby said train may be driven at one speed when said motor is operated by a current of any one of several standard frequencies.

BENJAMIN E. LAWRENCE. BENJAMIN HAYES. 

